Typical photographic elements use silver halide emulsions, the silver halide having a native sensitivity to ultraviolet UV radiation ("UV"). UV radiation is usually regarded as anything less than about 400 nm. Such UV sensitivity is usually undesirable in that it produces an image on the photographic element which is not visible to the human eye. In addition, in the case of color photographic elements, in particular, color dye images formed on the light sensitive emulsion layers by color development easily undergo fading or discoloration due to the action of UV. Also, color formers, or so-called couplers, remaining in the emulsion layers are subject to the action of UV to form undesirable color stains on the finished photographs. The fading and the discoloration of the color images are easily caused by UV of wavelengths near the visible region, namely, those of wavelengths from 300 to 400 nm. For the foregoing reasons, photographic elements typically incorporate a UV absorbing material in an upper layer.
Many types of UV absorbing materials have been described previously, and include those described in U.S. Pat. Nos. 3,215,530, 3,707,375, 3,705,805, 3,352,681, 3,278,448, 3,253,921, and 3,738,837, 4,045,229, 4,790,959. 4,853,471, 4,865,957, and 4,752,298, and United Kingdom Patent 1,338,265. Known UV absorbing materials often have many undesirable characteristics. For example, they tend to color and form stains due to their insufficient stability to UV, heat, and humidity. Also, a high-boiling organic solvent is usually required for the emulsification of the UV absorbing agents, which softens the layer and substantially deteriorates interlayer adhesion. In order to prevent these problems, a large amount of gelatin has been used in the layer containing the UV absorbent, resulting in a layer which may be unstable. Alternatively, a separate gelatin protective layer was provided over the UV absorbent containing layer. Such approach results in an undesirable thickening of the element. Furthermore, previously known UV absorbing agents, when provided in the uppermost layer of a photographic element, often migrate and crystallize at the surface of the layer. Thus, a gel overcoat would be used to minimize this undesirable blooming phenomenon. Furthermore, the droplets of such UV absorbing materials, when prepared by the conventional emulsification method described above, usually have particle sizes greater than 200 nm thereby producing light scattering with resulting deterioration of the element's photographic properties. The toxicity of such UV absorbing agents has also become an important issue recently.
It is known that polymer latexes obtained by polymerization of UV absorbing monomers, can be utilized as UV absorbing agents which do not have many of the disadvantages described above. Polymeric UV absorbing polymer latexes and their preparation have been described in, for example, U.S. Pat. Nos. 3,761,272; 3,745,010; 4,307,184; 4,455,368; 4,464,462; 4,513,080; 4,340,664; GB 1,504,949; GB 1,504,950; British Patent 1,346,764; EP Application 0 190 003 and others.
Some polymer latexes containing polymers of certain specific structures, have been previously used in photographic elements. For example, U.S. Pat. No. 4,551,420 and U.S. Pat. No. 4,464,462 describe photographic elements with polymer latexes. U.S. Pat. No. 4,943,519 describes the use of latexes formed from various ultraviolet absorbing polymers in photographic film. U.S. Pat. No. 4,528,311, U.S. Pat. No. 4,611,061, and U.S. Pat. No. 4,716,234 describe the use of polymeric UV absorbers containing units formed from 2-hydroxy-3-alkyl-5-(methacryloxyalkyl)-2-benzotriazole for use in contact lenses and intraocular lenses.
These polymeric UV absorbers (a UV absorbing compound sometimes being referenced herein as "UVA") have one or more of the following problems: (1) the UV absorbing monomer itself is hard to synthesize; (2) the UV absorbing monomer is hard to polymerize by emulsion polymerization; (3) the absorption spectrum of the polymeric UV absorber is not desirable; (4) the light stability of the polymeric UV absorber is relatively poor; (5) the photographic performance of the polymeric UV absorber, such as fresh Dmin (that is, the minimum density), dye fade, and dye stain, are not satisfactory. It is thus desirable to have a photographic element which uses a polymeric UV absorbing compound which has at least one of the foregoing characteristics improved.